title: Gold(I)-catalyzed benz[c]azepin-4-ol synthesis by intermolecular [5 + 2] cycloaddition.
abstract: A gold(I)-catalyzed intermolecular formal [2 + 5] cycloaddition for the preparation of benzofused N-heterocyclic azepine products is presented. A number of benz[c]azepin-4-ol products were readily prepared in one step from easily accessible phenylpropargyl acetals and benzaldimine substrates in the presence of a gold(I) catalyst. A direct one-pot procedure from the propargyl and the respective aldehyde and amine substrates was successful as well. The reaction to access the benzofused azepines could be rationalized by a cascade reaction, including a nucleophilic benzaldimine N-attack at a highly reactive phenylpropargyl-gold(I) carbenoid complex, generated from propargyl acetal. A subsequent deauration step promotes ring closure by 1,7-electrocyclization through an intramolecular Pictet-Spengler-type reaction with the aldiminium moiety.
authors.affiliation: Department of Chemistry, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.
authors.forename: Naseem
authors.initials: N
authors.lastname: Iqbal
authors.forename: Anne
authors.initials: A
authors.lastname: Fiksdahl
mesh_terms: D001552:Benzazepines / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D003500:Cyclization; D006046:Gold / Q000737:chemistry*; D015394:Molecular Structure
chemical_list: D001552:Benzazepines; D006046:Gold